Before You Buy GPS

You've watched from the sidelines as the perceptions of other farmers about GPS technology evolved from "It'll never work” to "I wouldn't farm without it.” You've observed your neighbors, studied their fields and done your homework. It's time to write some checks and bring GPS technology to your farm.

There will be challenges. There will be times when you'll want to pitch all the displays, wiring harnesses and owner's manuals out of the cab and go back to "just farming.”

But there will also be a moment when you push a button and the tractor, combine or sprayer starts laying out precise, straight swaths and you'll want to stand on top of the cab and shout, "I'm king of the world!”

It's a big jump from sitting on the technological sidelines to that moment of triumph. To help take the plunge into this technology, here are 12 things you need to know before you buy a GPS system:

The basic concept of GPS technology.

The Global Positioning System (GPS) uses a network of satellites to calculate the precise location of a vehicle, piece of farm equipment or hand-held receiver on the face of the Earth.

GPS systems have multiple uses on modern farms.

There are many ways farmers can use GPS technology on the farm:

Yield mapping blends on-the-go yield data with GPS information to create maps that show how yields vary across your fields.

GPS-based guidance systems help direct machines through fields, eliminating the need to follow rows or use mechanical or foam markers.

GPS-guided automated planter and spray boom section controls track a machine's field location and turn on or off planter row units or boom sections as it overlaps previously planted/sprayed areas or passes through no-spray/no-plant areas.

GPS-aided manual guidance is as simple as it gets: The operator pushes a button to establish "Point A,” then drives for a distance and pushes the button again to establish "Point B.” The computer uses GPS technology to create an imaginary, invisible straight line, called an "A–B line,” between the points. It also creates a series of imaginary lines parallel to the A–B line.

On subsequent passes, the operator watches a lightbar or visual display and manually steers to follow those electronic "marks.”

GPS-guided auto-steer systems actually steer machines through the field. Once an A–B line is established and the operator pushes a button to engage auto-steer, the system takes over and steers the machine.

System manufacturers offer alternatives to straight A–B lines for circle-irrigated fields, contoured fields and fields where rows can't run straight.

GPS systems offer varying degrees of precision.

Precision is defined in two ways: accuracy and repeatability.

Accuracy refers to how much an A–B line can vary. If a system advertises 4" to 6" accuracy, it means the A–B line could waver as much as 4" to 6" sideways across the field.

Repeatability is the stability of the A–B line over time. The reasons are complex, but an A–B line established at 8 a.m. can "move” and be offset several yards by sunset due to satellite positions. Repeatability becomes an issue if a farmer wants to precisely follow the same tracks throughout a growing year or strip-till fertilizer in November and then plant precisely into the fertilized strips in May.

Know your goals.

"Before you even think about buying [GPS] technology, consider what you want to do on your farm,” says Sid Siefken of Trimble. "Do you want to plant straighter rows? Apply fertilizer more accurately and efficiently? Maybe you just want to be less tired at the end of the day. A good dealer will listen to your needs and help you select the right levels of GPS technology.”

Avoid getting stuck in a technological dead end.

Even if you don't want to go whole hog with your first GPS system, be sure that system can expand as your needs expand.

"The cheapest option is not always the best value,” Siefken says. "Ask your dealer what each system offers and how it can be upgraded. Can you start out using it as a lightbar [guidance system] and then upgrade to automated steering later? Future-proof your technology by starting with equipment that is highly functional now and has built-in capabilities for upgrades later.”

GPS systems require a "modern mindset.”

If you don't have a home computer, if you don't have a cell phone, or if you despise "pushing buttons,” then GPS technology may be a challenge. Modern GPS systems are extremely user-friendly but assume users have basic computer skills.

"There's a definite learning curve that you need to be prepared for,” says Shannon Bryan, a Dawson, Iowa, farmer. "I can't say I'm adept at computers, but I've had one in the house since the '80s and am comfortable entering information and moving around the system. I started yield mapping 12 years ago and use computerized spray controllers, so it really wasn't a big problem to learn how to set up and use [GPS-guided] auto-steer.

"One advantage I have is my age,” chuckles the 50-something Bryan. "I'm old enough to have a son who isn't afraid of computers. If there's something I can't figure out, I give him the owner's manual and he tells me which buttons to push.”

You can't "break” GPS software, but you can lose information.

An operator cannot damage or destroy a system by pushing a wrong button. "Poke and learn” is actually a valid way to answer the question, "What happens if I do this?” But it is possible to lose information—the width of the machine, type of machine, type of operation, field number, farm number, etc.—if you accidentally push the wrong button.

This information can be re-entered, but it takes time. Savvy operators keep hard copies of critical settings so they can re-enter data if necessary.

GPS systems require extra time.

Operators must be prepared to spend a half-hour to several hours updating and programming GPS systems each year. They must also be prepared to spend a few minutes updating or inputting data when they switch fields and farms. If you don't take time to freshen data when necessary, your GPS system may not work correctly.

GPS systems have "off” buttons.

If circumstances prevent an operator from making data inputs, or if a GPS component fails, in most situations the system can be turned off and the planter, combine, sprayer or other machine can be operated manually. Remember: The steering wheel works even if the GPS system doesn't.

GPS systems can pay for themselves.

Exact numbers vary from user to user, but industry experts say farmers can expect GPS systems to offer 3% to 7% time savings during tillage, planting and other field operations by reducing overlaps. Depending on the operation, minimizing overlap can reduce fuel use by 5% to 15%. Operators using high-accuracy GPS guidance can reduce fertilizer and chemical costs by 5% to 15%, simply because they aren't double-applying inputs. Planters with row shutoffs and variable-rate seeding systems have been documented to reduce seed costs by another 5% to 7%.

Intangible benefits.

"Now that I've used [GPS-guided] auto-steer, the stress reduction is bigger than I ever anticipated,” says Bryan, the Iowa farmer. "It's hard to put a dollar amount on how much less tired I am at the end of a day. One example is my shoulders and neck don't ache after a day running the planter like they used to. Intangibles like less stress are bonuses that sealed the deal for me.”